Signaling arrangement for four-wire circuits



C. 5. DEMAREST SIGNALING ARRANGEMENTTOR FOUR-WIRE CIRCUITS Filed m. 19, 1924 INVENTOR 61mm;

- ATTORNEY Patented Mar, 39,1926.

TELEPHONE AND TELEGRAPH COMPANY, ACORPORATIQN- OF 'NE'W' YORK; 1

' SIGNALING ARRANGEMENT on noun-WIRE cinemas.

' Application filed lanua ry 19,1324. seemin $687,377;

'To all whom it may concern: 7 a g Be it known that I, CHARLES S. DnMAnn-sr,

a citizen of the United States, residing at Ridgewood, in the county of Bergen and State of New Jersey, have invented certain Improvements in Signaling Arrangements for Four-VVire Circuits, of which the-following is a specification. 1 l I j This nvention relates to transmission 1 lines and more particularly to signaling arrangements for transmission lines of the Well known four-wire type. ;v

The signaling apparatus at a switchboard at which a transmission line terminates 'is usually designed to operate at relatively low frequency, such, for purposesof illustration, 'as a. frequency of the order 'of cycles, 'while the frequency utilized for transmission over the line itself is usually of v 20 a relatively higher order, such, for purposes of illustratiomas 135 cycles. Accordingly,

at the terminal of atransmissionlinea vdevice well known in the-.art and termed a composite ringer may be employed Such a device comprises means responsive to the relatively high frequency signaling currents \coming in over the line for controlling a leyice to apply relatively lowl frequency signaling currentsto' the switchboard apparatus, andv vice .vers'a'. It; .is the purpose of the invention to provide improved arrangements for associating composite ringer apparatus with a four-wire type of transmission line. As is well known, the fourwire type of transmission line comprises two one-Way line sections for transmission in opposite directions connected at a station through a hybrid coil, or three-winding transformer, to a terminal two-way line. It has been found in practice to be undesirable to associate the composite ringer ap-- paratus entirely with the terminal two-way line, as the signaling currents would have ally not designed-to be efiicient at the signal ing frequencies utilized. In accordance with the arrangements of this invention, the low frequency side of the composite ringer is as-'.

to be transmitted through the hybrid coil" in such instance, and the hybrid coll is generingsignals or may beconnected with-the outgoing loneway line for transmitting sig- -FATEnrorrica CHARLES s. ,DEMAREST, 0F nrnenwoon, NEW JERSEY, AssrGNo'a roAM-ERICAN nalsl With such an arrangement the trans,

mission of signaling currents through-the hybrid coil maybe avoidedfand the standard type'of composite set may beutilized with a -four-wire typeoftransmission line. Further; features and objects of theinvention" will appear more fully from the detailedfdes c ription hereinafter given.

The invention may be more fully under-f stood' from the following description to? gether with the accompanying drawing in the ,figure; of; which is illustrated a circuit gi gmm of the arrangements of the inven ion. I

The drawing""illustrates a portion ere four-wire transmission system comprising the outgoing one-way two-wire line sectionv L and the-incoming one-way two-wireline sectlon L These 111163 are co-nnected by the three-Winding --transf'ormer,.- orhybrid f with and terminates-linthe balancing netcoil, 1 to the' terminal two-Wire two-way I line L Theline L is connected inductively f work,N Tl1e cut oft' relay. 3 ishssociated with ,the'lineL andthe antificial{line or net- WorlcN -The composite ringerfapparatus i -6 'is shown enclosed in dottedlines-and is well knownin the 131 i); The: low; frequency branch of the ringer is connected to the termmal two-w1re line L byconductors-4 and 5 The high frequency branch of: the

composite ringer is" associated with lines L or L by means-of conductors '12 and 13 and the switching arrangements contr lled by relay 11.

The invention may be morefully under- 7 stood from the followingdescription of its operatiom The signaling currents coming in over the four-wlre system would be transm tted over the one-way line L and, as has been formerly pointed out,might be of a frequency of the order of 135 cycles. These signaling currents would be transmitted over conductors 16 and 17 and the break contacts of relay. 11. and over conductors 12, and 13,

break contacts of relay 9 and throughthe winding of relay 18 thereby actuating relay following circuit:

18. The actuation of relay 18 will close the.

From ground, armature and contact relay 18, conductor 19, Winding of relay '21 to battery and ground; This will operate the relay 21 which will connect to the con ductors 4 and 5 a source of signaling current suitable for operating the apparatus at :the switchboard which might, inrpractice, be of a- )Erequ-ency of the order' of 20 cycles. This 20 cycle current will be transmitted over conductor 4 and 5Ta-11Cl thenceover the line L.

' tothe switchboard apparatus. 1 The operation A of relay 18 would also close auci-rcui-t from ground, armature and'contact ofrelay 18,v

con'ductor .19, conductor 22, enter 'leifth-and 7 break contact and armature of relay 111C011? ductor23, winding of cut-off rela'yfi tobat tery and ground. This will operate the cut;

" ofit relay 3 which will open -botli thelin'e L and'the artificial line N that the low frequency signaling currents gwillflnot be transmitted back over-the" line L5,] The sig naling' currents transmitted fromthe. switch- 7 board apparatus, which, as-has been pointed outmight have a fi'equency of the order of 20 cycles, would be transmitted overline, L

and. thence over conductorsi l' and 5 arma 1 tures and brealrcontactsof relay21 through thewin'ding of 'relay- T thereby actuating 'relay 7'. 'Theoperationofrelay 7" will close the following' circuit} I From ground andai'matureandcont-actof relay 7, conductorlS; winding ofrelay- 9 'to battery and ground and alsofgclose' a circuit 1 from conductor 8,- over conductor i 10, wind ing;ofre1ay 11 tobattery mag -011ml; This 13, make conta'ctsof relay" 1 1 and thenceover conductors 14: and 15 and outover the line L The operation of relay 11 will also close a circuit from ground outer left-hand make contact of relay-'11, conductor23, winding of cut-off relay 3to battery and ground thereby operating thecutofi' relay to prcvent any of these signaling currents from b8111 transmitted over the hue L0 to the V 2' i V k line L :VVhile the inYel ib deemed-advisable; it fis -understood that it is v has-been disclosed'iii I certain ,4 specific arrangements which are .Icap'able o fembodimentin many-other and i WldblYVEl-I'lil iorms without departing from the spirit of theinvention ,as defined in the following-claim.-

What1sc1a1med-1s: j V 'A transmission system comprising a terartificialline associated with said line, a

cut-off relay for opening said line and said artificial line, two one way 'lines'for transmission in opposite directions associated witlrsaid terminal line by said hybrid coiha composite ringer,=means for connecting one i branch of 's'aid ringer with: saidtermi-naltw'voway line, switching means associatedqwith saidtwo oneway linesfor connecting the other section of sand ringer with either or SalliOI1'8W9vy l1I1BS-meiIlS controlled by; said 7 ringer for ope-rating: said switehing means; and means controlled by-fsaid' switching means and; by said ringerifor operating said cutroffrelay; v f r 1 I In testimony ,wl1 eneof, I: ha e signed my name to this specification this-"16th January, 1 924.i

{dailies v CEARLESS} DEMARE$TQ 

